openlink
`datatype(?o)` is empty
I initially posted this question on stackoverflow and was advised to open a ticket here since it might be caused by "a relatively recently introduced bug".
I noticed that running the following query on dbpedia:
SELECT ?s, datatype(?s), ?p, datatype(?p), ?o, datatype(?o)
WHERE {
?s ?p ?o .
}
LIMIT 100
returns a response in which the column for datatype(?o) is blank. The first row returned by this query looks like this:
?s http://dbpedia.org/ontology/deathDate
datatype(?s) http://www.w3.org/2001/XMLSchema#anyURI
?p http://www.w3.org/1999/02/22-rdf-syntax-ns#type
datatype(?p) http://www.w3.org/2001/XMLSchema#anyURI
?o http://www.w3.org/2002/07/owl#FunctionalProperty
datatype(?o)
Running this same query on a local installation running Virtuoso version 7.2.6.3233 returns:
http://www.openlinksw.com/virtrdf-data-formats#default-iid
http://www.w3.org/2001/XMLSchema#anyURI
http://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://www.w3.org/2001/XMLSchema#anyURI
http://www.openlinksw.com/schemas/virtrdf#QuadMapFormat
NULL
where the value returned for datatype(?o) is NULL.
(I suspect that this behavior goes back to at least 2016: this question on stackoverflow asks why a query with a filter clause FILTER(datatype(?o) = xsd:integer) times out before returning any results across all of dbpedia, which I suspect is caused by the behavior describe above.)
Is this a bug or intended behavior?
